Method of preparing a powdered milk for ice-cream mix



Patented Feb. 21, 1928.

UNITED STATES 1,659,723 PATENT OFFICE.

ARTHUR S. COSLER, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-.HALF TO TURNEY PROCESSES, INQ, OF WASHINGTON, DISTRICT OF COLUMBIA, A CORPORATION OF DELAWARE.

METHOD OF PREPARING A POWDERED MILK FOR ICE-CREAM m No Drawing.

The invention is primarily a development or improvement on what is known as the Turney process as set forth in patents granted to Paul W. Turney, August 1, 1922,

y Nos. 1,424,602 and 1,424,603, particularly the latter patent, and relates broadly to ice .cream manufacture, and more particularly to a process for producing a powdered milk product to be used as an element in the manufacture or preparation of ice cream or ice cream mix.

Turney Patent No. 1,424,603, describes the manufacture of a binder, filler or stabilizer, consisti of a specially treated milk "product, whic can be used in ice cream manufacture in place of the artificial binders or fillers, other than milk products, previously used. In this filler, the casein particles have been increased in size and rendered jellylike, by the introduction into milk, preferably skim milk which has been previously partially evaporated, of a small quantity of alkali, with suflicient agitation of the mixture following the introduction of the alkali to incorporate the alkali into the casein particles, t ereby causing them to swell and develop a elatinous character.

The filler or inder produced according to v the above processis very satisfactory when I used in the liquid condition and possesses marked stabilizing properties. In commercial practice, however, it is fre uently desirable to produce the filler in t e form of a powder which may be kept for a considerable time without becoming rancid, and which, when reconstituted into milk to be used in an ice cream mix, will have binder or stabilizer properties equal to those possessed by the milk solids, not subsequently powdered, which have been prepared by the Turney process. Y

' It has been found, however, by experiment, that the filler roduced by the Turney process, when powd red, loses some of its i binder or stabilizing properties, and it is the principal object of the present invention to improve the Turney process so that a maxi- 'mum of the stabilizer effect is maintained,

even when the filler is reduced to powdered form.

I have found that by superheating and thickening the milk, from which the filler is produced just prior to the alkali treatment of the Turney process, a permanency Application filed April 25, 1927. Serial No.186,'597.

is imparted to the stabilizer or binder effect, which permits the filler 'to be reduced to a powder, and when reconstituted into milk to be used m the ice cream inix, its binder or stab1l1z1ng properties are bound to be substantially unimpaired.

It is not to be understood that I claim this superheatlngand thickening, broadly, as my inventlon, as the thickening effect imparted by such superheati has been known and practiced in the con ensing industry for a perlod of many years. I do, however, claim this superheatmg or thickening effect as a step or integral part in the preparation of a stabilized powdered filler for use in "ice cream mlx.

The powdered filler, produced by the process, 1s found to possess excellent binder propertles, and when used in ice cream makmg, renders unnecessary the use of any extraneous substance, such as gelatine, gum, glue, starch, egg yolk or other substances generally employed to impart such properties as smoothness'and standing up quality to ice cream.

Fo-r a full understanding of my inventron, a preferred embodiment thereof will now be described in detail, although it will be understood that the invention is not to be limited to such details.

In carrylng out the process either skim or whole milk may be employed for the product1on of the powdered milk containing a self constituted filler or binder, but it is found that the keeping qualities of powder from skim milk are better than a similar powder from whole milk, and accordingly I prefer to employ skim milk. This may be preferably concentrated or condensed in a suitable vacuum pan to the usual density, approximately three to one, or containing twenty-six to twenty-eight percent serum solids.

The milk is now treated by heating it above the coagulating point of lactalbumin but without scorching, the temperature ran 'e being from approximately 175 to 212 15,

depending on the character of the milk and other considerations. This step I refer to as superheating, and may be carried out on normal milk containing 8-9% of serum solids, though I prefer to employ milk from whicah1 a large part of the water has beeniremov a The superheating has the effect of thickening the milk appreciably. It is believed that the explanation for this action is that thelactalbumin, being intimately incorporated in the whole mass of milk, does not separate out as separate flocks, but coagulates in such I existing thus. in this state of intimate association tend to give more body to the mass, and the above noted thickening results. 4 j

Whatever the true explanation for the theory of such thickening or superheating may be, the fact remains that by the employment of this step in connection with the Turney process, the final powdered product possesses permanent binder or stabilizer properties, which it does not have where thls step is omitted.

This thickening cannot be carried out to the same degree in all milk, nor can the heating be carried as high in some milk without throwing out oncurdling the casein. The presence of acid, bacteria, and enzymes determine the degree of heating, and where these are present the process must be carried out at lower temperatures and the heating prolonged. Usually it may be said that the duration of treatment for condensed milkwill be from fifteen to thirty minutes, depending on the temperature it is judged best to use.

After superheating to thicken the milk, it is preferably allowed to cool to ordinary temperatures before the next stage of the process is undertaken, but this is not absolutely essential.

A suitable alkali is now incorporated into the heat thickened-mass accompanied by rapid agitation. The agitating devices should be especially arranged to g1ve a ood circulation of the mass, so that the a kali will be thoroughly and uniformly distributed. There should also be a good beatin or mixing agitation so that any clots of thickjell may be broken up and a smooth mass'will result.

The alkali used is preferably calcium hydrate. Where the calcium hydrate is used it may be added in the form of a cream made from (pure calcium oxide and water. If preferre a quantity of sugar may be added to the calcium hydrate to orm calcium sucrate. It should be noted that the calcium oxide may be replaced by other alkalies, in whole or in part. The specific effect sought for on the final product is not, however, due to sim le neutralization. While other alkalies wil neutralize as well or better than lime, and give the gelatinizing effect, they do not producethe same binder'or stabilizing effect R m the final ice cream product, that is obvover a few hundredths of a per cent lactic acid. When calcium hydrate or sucrate is added, part combines with the acid, and part with casein, making the latter more soluble, the particles probably taking up water and becoming jelly-like.

While this action of the lime on casein can thus only be brought about by practically neutralizing the lactic acid in the milk, it is definitely due to a cause separate from the neutralization itself. It is the properties of the calcium caseinate formed at this stage by adding the alkali (calcium oxide) equivalent to to ounces per gallon of normal sweet milk, to the thickened milk prodnot which appears to be responsible for the stabilized qualities of the final powder. The proportions of the alkali may be varied slightly from those above set forth, but should be maintained approximately.

Following the thickening and alkali treatments, the milk may be reduced to a powder or flakes in any suitable manner, being preferably forced under high pressure through spra nozzles, and" dried in the customary air rying systems. 1

The powder so produced may be kept for long periods, without deterioration. When used in making ice cream the powder may be reconstituted into milk by dissolving directly in water, preferably with agitation, and the reconstituted milk will be found to possess all the thickening properties'desirable in a first class binder, which may be used as an consists in thickening milk b. heating at atemperature above the coagu ating point of lactalbumin but without scorching, adding thereto an alkaline solution, agitating the mixture, then reducing the same to powder,

2. A method of making a powdered milk for ice cream mix or the like, which when reconstituted, will have marked binder or stabilizing properties, which process consists in heating milk to a temperature above the coagulating point of lactalbumin but without scorching, until a substantial thickening occurs, introducing thereinto a solution of calcium oxide with sugar, agitating the mix: ture, then reducing the same to powder.

3. A method of making a powdered milk for ice cream mix or the like, which, when reconstituted, will have marked stabilizing or binder properties, which method consists in thickening skim milk by heating to a temperature of from 175 to 212 F., adding thereto an alkali solution, agitating until a gelatine-like mass is produced, then drying and reducing the same to powder.

4. The method of making a powdered milk for ice cream mix or the like, which when reconstituted will have marked stabilizing or 'ing same to pow binder properties, which process consists in reducing the fluidity of the milk, superheating the same at a temperature above the coagulating point of lactalbumin but without scorching, adding thereto a proportion of alkali of such relatively small quantity as to be substantially imperceptible in the final product, agitating the mixture, then reduc- 5. A method of making powdered milk for ice cream mix or the like, which when reconstituted, will have marked stabilizing or hinder properties, which process consists in heating milk to a temperature above the coagulating point of lactalbumin but Without scorching, until a substantial thickening occurs, introducin thereinto a solution of calcium oxide, agltating the mixture, then reducing the same to powder.

In testimony whereof I aflix my signature.

ARTHUR S. COSLER. 

